The dynamics of two-phase gas-liquid flow in pipes can be very complicated. Differences in the liquid and vapor densities and velocities create two-phase flow patterns or regimes, as shown in FIG. 1. These flow regimes can range from homogeneous bubble or mist flow to stratified flow to intermittent slug flow. The occurrence of a particular flow regime depends upon the amount of gas and liquid present in the pipe, their velocities, densities, and viscosities. Additionally, the flow regime can vary along the length of the pipe as a result of mass transfer between the vapor and liquid phases, as is the case when heat loss occurs in steam pipelines. The fluid dynamics created by such two-phase flow regimes make it very difficult to apply conventional single-phase metering methods reliably and accurately.